Patent document 1 described below discloses a multiband direct conversion wireless communication device that is able to demodulate a desired signal by protecting the desired signal from the effects of interference waves.
In this multiband direct conversion wireless communication device, signals in a plurality of frequency bands are received by a single antenna terminal. These reception signals are supplied from the antenna terminal into a single bandpass filter via a duplexer and a low-noise amplifier (LNA). The reception signals are supplied from the bandpass filter into an I-channel mixer and a Q-channel mixer with differential inputs, and they are then down-converted into baseband signals by local signals supplied to the I-channel mixer and the Q-channel mixer from a local oscillator.
[Patent document 1] Published Japanese Translation No. 2004-521534 of the PCT International Publication